1. Field of the Invention.
This invention is directed to mixer circuits, in general, and to balanced, star configured mixer circuits, in particular.
2. Prior Art.
Mixer circuits of many varieties are known in the art. Many of these known mixer circuits are arranged to be symmetrical in configuration and operation. However, these circuits typically utilize toroids or transformers to effect signal coupling. There are several disadvantages of such toroidally coupled mixer circuits. For example, the transformers have to be wound by hand and then they have to be hand tuned. Thus, when the mixer is assembled, it is, typically, tested on a network analyzer and each one of the transformers is hand tuned. This operation is, of course, time consuming and expensive.
Furthermore, these standard mixers tend to be fairly bulky and require a substantial amount of space in a circuit application.
Likewise, in the standard mixer, the control signals from the local oscillator (i.e. the driving circuit) must be large enough to turn on the diodes which are included in the circuit. This means that the control signals can become rather large relative to the circuit application.